In schools, offices, theaters and other public buildings as well as residential quarters it is often desirable to provide means for automatically controlling the temperature in a predetermined manner, generally by changing the setting of a thermostat, in order to insure a comfortable level during hours of use and to minimize the expenditure of energy at other times, e.g. at night or on weekends. Seasonal changes, business schedules and other extraneous conditions usually require modifications of the daily on/off periods over cycles of one week or longer.
The use of a manually programmable read-only memory for generating switching commands at selected times of an invariable cycle, e.g. during a 24-hour period, has already been described in commonly owned U.S. Pat. No. 4,164,665 in the name of Hans Berger. According to the teachings of that patent, primary and secondary conductors on a printed-circuit board can be selectively interconnected by jumpers inserted through slits in an overlying cover plate. A scanning circuit operating in real time successively energizes different combinations of primary and secondary conductors to generate an output signal whenever the energized conductors are interconnected by a jumper. This output signal serves as a switching command for the control of a load such as the thermostat of a heating plant.
For modifying the duration of the program cycle of a read-only memory operating in real time, the only known system of which I am aware is the one described in German utility model No. 7,824,156 of Aug. 9, 1978 which uses a rotating program carrier whose speed of rotation can be changed, e.g. from one revolution per day to one revolution per week, with the aid of a gear shifter.